Linear motor control apparatus and linear motor control system

ABSTRACT

A linear motor control apparatus has: a plurality of coil units; a plurality of position detecting units for detecting positions of a plurality of trucks which move over the plurality of coil units; a plurality of deviation calculating units for operating deviation information as differences between the detected truck positions and a target position of the detected truck; a plurality of position control units for operating current control signals based on the deviation information; a plurality of current control units for supplying driving currents to the coil units based on the current control signals; and a switching unit for switching the position control units to which the deviation information is transmitted or switching the current control units to which the current control signals are transmitted.

CROSS REFERENCE TO RELATED APPLICATION

This application is a Divisional of U.S. patent application Ser. No.15/788,872, filed on Oct. 20, 2017, which is a Divisional of U.S. patentapplication Ser. No. 14/682,412, filed Apr. 9, 2015, now U.S. Pat. No.9,847,742, issued Dec. 19, 2017, and which claims priority to JapanesePatent Application No. 2014/086367, filed on Apr. 18, 2014, the entiredisclosures of which are all incorporated by reference herein in theirentireties.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a linear motor and, more particularly,to a linear motor control apparatus of a linear motor of a moving magnettype and a linear motor control system.

Description of the Related Art

A linear motor of a moving magnet type has such a construction that amagnet is arranged in a truck serving as a needle and a coil is arrangedin a stator, respectively, and is suitable for conveyance of a longstroke as compared with a linear motor of a moving coil type in which anelectric wire is connected to a truck. In such a moving magnet typelinear motor, when a driving stroke longer than a size of needle isnecessary, a plurality of coils corresponding to a stroke length arenecessary. Generally, the moving magnet type linear motor has such aconstruction that a plurality of coils are arranged and connected to acurrent controller so that current control by three phases can be made(refer to Japanese Patent No. 2831166). According to such aconstruction, if all of the three-phase coils are connected to the samecurrent controller so that those phases are serially connected, a thrustcan be generated. However, it is difficult to individually control theplurality of trucks on the same conveying path.

Therefore, a coil unit comprising a plurality of coils is constructed, alinear motor module having a motor controller for controlling a positionof one truck is constructed so as to correspond to one coil unit, and aplurality of trucks are individually controlled.

Generally, such a construction that a plurality of linear motor modulesare continuously arranged, a long stroke conveyance is attained, and theplurality of trucks on the same orbit are controlled is known.

In a conveying apparatus for FA (Factory Automation), it is requiredthat a plurality of trucks are arranged at a high density, the truck ismoved at a high speed, the truck is stopped at a high precision, and arestriction to a stop position of the truck is small.

However, in such a construction that the linear motor modules are simplyarranged, when one truck stops at a boundary position between theadjacent linear motor modules, the truck stops at a boundary positionbetween the adjacent coil units. In this case, since the truck issimultaneously controlled from two motor controllers for respectivelycontrolling the adjacent coil units, it is difficult to stop the truckat a high precision.

In the case of controlling one truck by using the motor controller ofone of the adjacent linear motor modules, although the truck can bestopped by driving one of the coil units, a thrust which is applied tothe truck is reduced to the half. On the other hand, in order to allowthe truck to obtain a thrust which is equal to that in the case whereboth of the adjacent coil units were driven, it is necessary to supply adouble driving current to one coil unit and costs of an electric circuitare high. Therefore, such a construction is undesirable.

According to Japanese Patent No. 2831166, a thrust command serving ascurrent control information is generated by one position detector andone motor controller and the same thrust command is transmitted to aplurality of current controllers, thereby driving a plurality ofcontinuous coil units and controlling one truck. However, according tosuch a construction, although the truck can be stopped at the boundaryposition between the coil units while keeping the thrust which isapplied to one truck, a plurality of trucks cannot be controlled.

SUMMARY OF THE INVENTION

The invention is made to solve the foregoing problem and it is an aspectof the invention to provide a linear motor control apparatus whichenables a plurality of trucks which move at a high speed to becontrolled at a high precision.

To accomplish the above aspect, according to the invention, there isprovided a linear motor control apparatus comprising: a plurality ofcoil units which are continuously arranged; a plurality of positiondetecting units configured to detect positions of a plurality of truckswhich move over the plurality of coil units; a plurality of deviationcalculating units configured to calculate deviation information servingas differences between the detected positions of the trucks and a targetposition; a plurality of position control units configured toarithmetically operate current control signals on the basis of thedeviation information; a plurality of current control units configuredto supply driving currents to the plurality of coil units on the basisof the current control signals; and a switching unit configured toswitch the position control units to which the deviation information istransmitted or to switch the current control units to which the currentcontrol signals are transmitted.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate exemplary embodiments, features,and aspects of the invention and, together with the description, serveto explain the principles of the invention.

FIG. 1 is a schematic constructional diagram of a linear motor controlsystem according to the first embodiment of the invention.

FIG. 2 is a schematic constructional diagram of a linear motor moduleaccording to the first embodiment of the invention.

FIG. 3A is an operation explanatory diagram of the linear motor moduleaccording to the first embodiment of the invention and is a top view ofa part of a moving magnet type linear motor illustrated in FIG. 2.

FIG. 3B is a top view illustrating a coil unit in FIG. 3A.

FIG. 3C is a side elevational view of the coil unit illustrated in FIG.3B.

FIG. 4A is a diagram illustrating control areas of the coil units.

FIG. 4B is a graph illustrating a target position of a truck atpositions illustrated in FIG. 4A.

FIG. 4C is a graph illustrating a target position of the truck atpositions illustrated in FIG. 4A.

FIG. 4D is a graph illustrating a target position of the truck at thepositions illustrated in FIG. 4A.

FIG. 5A shows control states illustrating the movement of the trucks.

FIG. 5B shows control states illustrating the stop of the trucks.

FIG. 5C shows a control state of a truck which enters newly.

FIG. 5D shows control states illustrating the stop of the trucks.

FIG. 6 is a flowchart illustrating control of the trucks according tothe first embodiment of the invention.

FIG. 7 is a flowchart illustrating an allocating process of the trucksillustrated in FIG. 6.

FIG. 8 is a schematic constructional diagram of a linear motor moduleaccording to the second embodiment of the invention.

FIG. 9 is a detailed diagram of position controllers and currentcontrollers in the linear motor module illustrated in FIG. 8.

FIG. 10A shows a control state illustrating the movement of the trucks.

FIG. 10B shows a control state illustrating the stop of the trucks.

FIG. 10C shows a control state of a truck which enters newly.

FIG. 10D shows a control state illustrating the stop of the trucks.

FIG. 11 is a flowchart illustrating control of the trucks according tothe second embodiment of the invention.

FIG. 12 is a flowchart illustrating an allocating process of the trucksillustrated in FIG. 11.

FIG. 13 is a schematic constructional diagram of a manufacturing systemaccording to the third embodiment of the invention.

FIG. 14A is a top view of a linear motor.

FIG. 14B is a cross sectional view taken along the line 14B-14B in FIG.14A.

DESCRIPTION OF THE EMBODIMENTS

Preferred embodiments of the present invention will now be described indetail in accordance with the accompanying drawings.

First Embodiment

The first embodiment of the invention will be described hereinbelow withreference to the drawings. FIG. 1 is a schematic constructional diagramof a linear motor control system 1 according to the first embodiment ofthe invention. As illustrated in FIG. 1, the linear motor control system1 has: linear motor modules 10 a to 10N serving as linear motor controlapparatuses; and a running controller 20 serving as a running controlunit. The linear motor control system 1 is a moving magnet type linearmotor. In the embodiment, for example, the linear motor control system 1has the N (N is an integer of 2 or more) linear motor modules 10 a to10N.

The linear motor modules 10 a to 10N are continuously arranged andconstruct one conveying path. Trucks which move in the linear motorcontrol system 1 are controlled by the linear motor modules 10 a to 10Nand move or stop on the conveying path.

The running controller 20 controls the linear motor modules 10 a to 10N.When describing in detail, for all trucks existing in the linear motorcontrol system 1, the running controller 20 transmits a driving profileserving as a driving command showing a target position of the truck totime to the linear motor modules 10 a to 10N. The running controller 20transmits a start signal serving as a group conveying command to thelinear motor modules 10 a to 10N so as to move, in a lump, the trucksexisting in the linear motor control system 1. When the operations ofthe linear motor modules 10 a to 10N become abnormal, the runningcontroller 20 receives error signals from the linear motor modules 10 ato 10N and, for example, makes control to stop all of the linear motormodules 10 a to 10N, or the like.

FIG. 2 is a schematic constructional diagram of the linear motor module10 a according to the first embodiment of the invention. FIG. 3A is atop view of a part of the moving magnet type linear motor illustrated inFIG. 2. FIG. 3B is a top view illustrating a coil unit in FIG. 3A. FIG.3C is a side elevational view of the coil unit illustrated in FIG. 3B.Each of the linear motor modules 10 b to 10N has a construction similarto that of the linear motor module 10 a illustrated in FIG. 2. In FIGS.2 and 3A to 3C, it is defined that an X axis is a progressing directionin which trucks 111 and 112 move, a Y axis is a horizontal directiondirecting toward a scale 205 when seen from the truck 111, and a Z axisis a vertical direction in which the trucks 111 and 112 are assumed tobe an upper side when seen from coil units 101 to 104.

The linear motor module 10 a has the plurality of coil units 101 to 104.By continuously arranging the plurality of coil units 101 to 104, aconveying path of the trucks 111 and 112 is formed. In detail, asillustrated in FIG. 3A, by arranging two rails 201 and 201 onto anapparatus stage (not shown) in parallel, the conveying path for thetrucks 111 and 112 is formed. By continuously arranging the plurality ofcoil units 101 to 104 between the two rails 201 and 201, the linearmotor conveying path of a long stroke is formed.

The trucks 111 and 112 have the same specifications and each truck has:magnets 114 to 116 serving as needles; the scale 205; and a moving block(not shown). The moving blocks and the rails 201 are membersconstructing a linear guide. The linear guide moves along the rails 201through a plurality of balls held in the moving blocks. The trucks 111and 112 having such moving blocks move along an orbit formed by the tworails 201 and 201 by the linear guide. The embodiment is merely shown asan example and may have a monorail structure constructed by a singlerail 201.

In the embodiment, in each of the coil units 101 to 104, a plurality ofcoils 105 are arranged so as to enable a three-phase driving comprisinga plurality of phases, that is, a U phase, a V phase, and a W phase. Asillustrated in FIGS. 2, 3B, and 3C, the coil unit 101 is constructed bysix coils 105 in which every two coils 105 of the U phase, V phase, andW phase are serially connected. Each of the coil units 102 to 104 alsohas a construction similar to that of the coil unit 101.

Although the coil unit 101 is constructed by combining the plurality ofcoils 105 and cores formed with flat rolled magnetic steel sheets andstrip, it may be constructed without using any core. Although a lengthof one coil unit 101 may be set to, for example, 100 mm, it is notlimited to such a length. The number of coil units 101 which areserially connected is not limited but the coil unit 101 may beconstructed by three coils forming three phases of the U phase, V phase,and W phase.

The coil units 101 to 104 continuously arranged as illustrated in FIG. 2are respectively electrically connected to current controllers 121 to124 serving as current control units by electric lines such as powerelectric wires. Each of the current controllers 121 to 124 suppliescurrents to each of the corresponding coil units 101 to 104 in such amanner that a current Iu of the U phase is supplied to a coil 105U, acurrent Iv of the V phase is supplied to a coil 105V, and a current Iwof the W phase is supplied to a coil 105W, respectively. Thus, each ofthe coils 105U, 105V, and 105W is excited by the current supply and eachof the coil units 101 to 104 can control the trucks 111 and 112.

The current controllers 121 to 124 are connected to a currentinformation selector 125 serving as a switching unit. The currentcontroller selected by the current information selector 125 supplies adriving current to the corresponding coil unit. The current informationselector 125 is connected to motor controllers 130, 140, and 150. On thebasis of current control information exchange signals which aretransmitted from the motor controllers 130, 140, and 150, the currentinformation selector 125 selects one or a plurality of currentcontrollers 121 to 124 as input destinations of the current controlinformation which is output from the motor controllers, and switches theselected ones of the current controllers 121 to 124. The current controlinformation exchange signal is a signal for allowing the currentinformation selector 125 to select one or a plurality of currentcontrollers for supplying the currents to the coil units for controllingthe truck as a control target. Although the motor controller 130 will bedescribed hereinbelow, each of the motor controllers 130, 140, and 150has the same construction.

The motor controller 130 has: a position commander 131 to make runningcontrol of the truck; a control deviation calculator 132 serving as adeviation calculating unit; and a position controller 133 serving as aposition control unit. The position commander 131 outputs positioncommand information serving as a target position of the truck as acontrol target to the control deviation calculator 132. The positioncommander 131 outputs the position command information of the truck tothe control deviation calculator 132 on the basis of the driving profiletransmitted from the running controller 20. The control deviationcalculator 132 calculates a difference between the position commandinformation which was output from the position commander 131 and theposition of the truck which is output from one of a plurality of opticalencoders 161 to 164 and outputs an obtained difference as controldeviation information.

The position controller 133 makes PID (Proportional Integral DerivativeController) control by the control deviation information calculated inthe control deviation calculator 132 and outputs current controlinformation serving as a current control signal. The current controlinformation exchange signal which is output from the motor controller130 may be formed by the position controller 133.

The motor controller 140 has a position commander 141, a controldeviation calculator 142, and a position controller 143. The motorcontroller 150 has a position commander 151, a control deviationcalculator 152, and a position controller 153. The position commanders141 and 151 have the same function as that of the position commander131. The control deviation calculators 142 and 152 have the samefunction as that of the control deviation calculator 132. The positioncontrollers 143 and 153 have the same function as that of the positioncontroller 133. Although the linear motor module 10 a has the threemotor controllers 130, 140, and 150 in the embodiment, it is sufficientthat there are motor controllers of the number as many as the number oftrucks serving as control targets and the number of motor controllers isnot limited to three. The driving profile transmitted from the runningcontroller 20 to each of the motor controllers 130, 140, and 150 may bestored into a memory (not shown) which can be accessed by each of theposition commanders 131, 141, and 151.

By detecting the position of the scale 205 by the optical encoders 161to 164 serving as position detecting units, the positions of the trucks111 and 112 can be identified. In the embodiment, a relation between thepositions where the plurality of optical encoders 161 to 164 arearranged and a length of scale 205 is such a relation that even if thetrucks 111 and 112 are located at any positions on the linear motorconveying path, they can be detected.

It is desirable that the optical encoders 161 to 164 have a resolutionof a few μm per count. In the embodiment, the optical encoder 161 isarranged in such a manner that a detection range of the optical encoder161 corresponds to a control area of the coil unit 101. Similarly, theoptical encoders 162 to 164 are arranged in such a manner that detectionranges of the optical encoders 162 to 164 correspond to control areas ofthe coil units 102 to 104, respectively.

The layout of the optical encoders 161 to 164 is not limited to such alayout and the number of optical encoders which are arranged is notlimited. Although the embodiment has been described with respect to theoptical encoders 161 to 164, the invention is not limited to the opticalencoders but arbitrary encoders may be used so long as the positions ofthe trucks can be detected and, for example, magnetic encoders may beused. For example, it is possible to use such a layout that a pluralityof encoders are arranged at regular intervals to the control area of onecoil unit 101, the encoders are continuously switched in accordance withthe positions of the trucks, and the positions are detected. Althoughabsolute type encoders are used as optical encoders 161 to 164 in theembodiment, the optical encoders 161 to 164 are not limited to theabsolute type but may be an increment type.

A position information selector 165 serving as a selecting unit isconnected to the optical encoders 161 to 164, respectively. Referencecharacters a, b, and c of the position information selector 165illustrated in FIG. 2 denote that they are connected to thecorresponding reference characters a, b, and c, respectively. That is,the position information selector 165 is connected to the controldeviation calculators 132, 142, and 152 provided for the motorcontrollers 130, 140, and 150, respectively.

A controller 170 serving as an allocating unit is connected to theposition information selector 165 and is further connected to the motorcontrollers 130, 140, and 150, respectively (not shown). The controller170 allocates the trucks detected by the optical encoders 161 to 164 toany one of the motor controllers 130, 140, and 150 and transmits aposition information selection signal serving as allocation informationto the position information selector 165. On the basis of the positioninformation selection signal transmitted from the controller 170, theposition information selector 165 can combine any one of the motorcontrollers 130, 140, and 150 and any one of the optical encoders 161 to164 so that they can communicate with each other.

From each of the motor controllers 130, 140, and 150, the controller 170receives control state information showing whether each of the motorcontrollers 130, 140, and 150 is controlling the trucks 111 and 112 oris in a rest state where it does not control the trucks 111 and 112. Thecontroller 170 stores the control state information into a memory or thelike (not shown) so that the positions of the trucks detected by theoptical encoders can be transmitted to the motor controller in the reststate.

Control of the trucks using the linear motor modules will be describedhereinbelow. FIG. 4A is a diagram illustrating the control areas of thecoil units 101 to 104. FIG. 4B illustrates a target position of thetruck 111 at positions P1 and P2. FIG. 4C illustrates a target positionof the truck 111 at positions P2 to P3. FIG. 4D illustrates a targetposition of the truck 111 at positions P3 to P4. FIG. 5A shows a controlstate in the movement of the trucks 111 and 112. FIG. 5B shows a controlstate at the stop of the trucks 111 and 112. FIG. 5C shows controlstates of the trucks 111 and 112 and a truck 113 which enters newly.FIG. 5D shows a control state at the stop of the trucks 111 and 113.FIG. 6 is a flowchart illustrating control of the trucks 111 to 113 inFIGS. 5A to 5D. FIG. 7 is a flowchart illustrating such a process thatthe controller 170 allocates the positions detected by the opticalencoders to the motor controllers 130, 140, and 150. FIGS. 5A to 5Dillustrate a state where the control of the trucks 111 to 113 istime-sequentially arranged. In FIGS. 4A and 5A to 5D, the linear motormodule 10 b will be described and it is assumed that the linear motormodule 10 b is located between the linear motor modules 10 a and 10 c soas to be adjacent thereto. Although the flowcharts shown in FIGS. 6 and7 will be described with respect to the control of, for example, thelinear motor module 10 b, it is assumed that the linear motor modules 10a to 10N are also similarly controlled.

As illustrated in FIG. 4A, a range where the coil unit 101 can controlthe truck 111 corresponds to a control area 401 and, when the truck 111exists in the control area 401, the coil 101 is in a driving state.Similarly, a range where the coil unit 102 can control the truck 111corresponds to a control area 402. A range where the coil unit 103 cancontrol the truck 111 corresponds to a control area 403. A range wherethe coil unit 104 can control the truck 111 corresponds to a controlarea 404.

A position detection area 411 is an area where the optical encoder 161can detect the position of the truck. Similarly, an area where theoptical encoder 162 can detect the position of the truck is a positiondetection area 412. An area where the optical encoder 163 can detect theposition of the truck is a position detection area 413. An area wherethe optical encoder 164 can detect the position of the truck is aposition detection area 414. In the position detection areas 412 to 414,an area in which a portion shown by a broken line and a portion paintedin black are combined is an area where the position of the truck can bedetected.

In the optical encoders 161 to 164, the position detection areas of theadjacent encoders overlap.

Therefore, it is now assumed that the portions shown by the broken linesin the position detection areas 412 to 414 are areas which do notcontribute to the position of the truck 111. For example, the controller170 or the like couples the four position detection areas 411 to 414 asdata, thereby regarding as if they correspond to a position detected byone encoder. Therefore, in the case of detecting as a position of thetruck 111 near a boundary between the coil units, for example, near aboundary between the coil units 101 and 102, the position of the truck111 in the whole coil units 101 to 104 can be obtained. The process forcoupling the position detection areas 411 to 414 as data is not limitedto the controller 170 but may be executed by the position informationselector 165 or by the control deviation calculators 132, 142, and 152,respectively.

The position P1 is a position corresponding to an edge of the linearmotor module 10 b, that is, an edge of the coil unit 101 on the sidewhere the truck enters from the adjacent linear motor module 10 a. Theposition P2 corresponds to a position of a boundary between the coilunits 102 and 103 and is a stop target position of the truck. A positionP3 corresponds to a position of a boundary between the coil units 103and 104 and is a stop target position of the truck. A position P4 is aposition corresponding to the edge of the linear motor module 10 b, thatis, an edge of the coil unit 104 on the side where the truck progressesto the adjacent linear motor module 10 c.

The graphs illustrated in FIGS. 4B to 4D indicate the target positionsof the positions P1 to P4 corresponding to a time and each of theposition commanders 131, 141, and 151 uses such a target position asposition command information of the truck. The running controllertransmits all of the position command information illustrated in FIGS.4B to 4D to each of the motor controllers 130, 140, and 150. Each of themotor controllers 130, 140, and 150 may store the target positionsreceived from the running controller 20 into, for example, a memory orthe like (not shown) so that the position commanders 131, 141, and 151can use them as position command information. Time to shown in FIGS. 4Cand 4D indicates time when each truck has started the movement from thepositions P2 and P3.

The control of the trucks will be described hereinbelow on the basis offlowcharts of FIGS. 6 and 7 with reference to FIGS. 5A to 5D. It isassumed that the target positions have already been transmitted from therunning controller 20 to each of the motor controllers 130, 140, and150. In FIGS. 5A to 5D, a stop position interval of the trucks is equalto hundreds of mm, for example, 200 mm. The flowchart shown in FIG. 6illustrates the control which is made after the running controller 20started the running of the trucks in a lump.

In FIG. 5A, on the basis of the flowchart of FIG. 7, the controller 170has already allocated the motor controller 130 to the truck 111 and hasalready allocated the motor controller 140 to the truck 112. It isassumed that the motor controller 150 is in a rest state and hastransmitted a signal showing that the trucks are not controlled to thecurrent information selector 125 and the controller 170. It is alsoassumed that the optical encoders 162 and 164 have transmittedinformation showing a state where there are no trucks, that is,information showing that the trucks whose positions are detected do notexist to the position information selector 165. Since each of the motorcontrollers 130 and 140 executes the same process, in step S604 andsubsequent steps in FIG. 6, the motor controller 130 will be described.

The optical encoders 161 and 163 detect the positions of the trucks 111and 112, respectively (step S601). In FIG. 5A, since the truck 111 islocated in the control area of the coil unit 101, the optical encoder161 detects the position of the truck 111. Since the truck 112 islocated in the control area of the coil unit 103, the optical encoder163 detects the position of the truck 112. The positions of the trucks111 and 112 detected by the optical encoders 161 and 163 are input tothe controller 170 through the position information selector 165.

Subsequently, the controller 170 determines whether or not a new truckto which the motor controller is not allocated in the trucks 111 and 112detected by the optical encoders 161 and 163 has entered (step S602). InFIG. 5A, since the truck which entered newly does not exist (NO in stepS602), the controller 170 does not allocate any motor controller. Instep S602, the controller 170 may determine the new truck, for example,on the basis of the presence or absence of the motor controllerallocated to the truck detected by the optical encoder.

In FIG. 5A, the truck 111 is controlled by component elements shown byportions painted in black. That is, the optical encoder 161 detects theposition information of the truck 111 and the position informationselector 165 transmits the position information of the truck 111 to thecontrol deviation calculator 132 of the motor controller 130. Similarly,the optical encoder 163 shown by a black frame line in FIG. 5A detectsthe position of the truck 112 and the position information selector 165transmits the position of the truck 112 to the control deviationcalculator 142 of the motor controller 140. On the other hand, the motorcontroller 150 shown by a broken line in FIG. 5A does not control thetrucks. The current controllers 122 and 124, coil units 102 and 104, andoptical encoders 162 and 164 do not contribute to the control of thetrucks 111 and 112.

The motor controller 130 calculates a difference between the targetposition of the truck 111 and the present position detected by theoptical encoder 161 and arithmetically operates control deviationinformation (step S604). In detail, the control deviation calculator 132calculates a deviation as a difference between the target position ofthe truck 111 which is output from the position commander 131 and thepresent position of the truck 111 detected by the optical encoder 161.

On the basis of the control deviation information calculated by thecontrol deviation calculator 132, the position controller 133arithmetically operates current control information including amagnitude and a direction of a current for controlling the currentcontroller (step S605). In step S605, the position controller 133 formsa current control information exchange signal for selecting one or aplurality of current controllers necessary to drive the coil units inaccordance with the position of the truck 111 among the currentcontrollers 121 to 124. The current control information exchange signalmay be formed on the basis of, for example, any one of the position ofthe truck 111, the target position, the calculated control deviationinformation, and the like. In the case of FIG. 5A, the truck 111allocated to the motor controller 130 is located in the control area 401of the coil unit 101. Therefore, the position controller 133 forms sucha current control information exchange signal that the currentinformation selector 125 can select the current controller 121 forsupplying the current to the coil unit 101.

The motor controller 130 transmits the current control informationarithmetically operated in step S605 and the formed current controlinformation exchange signal to the current information selector 125(step S606). On the basis of the current control information exchangesignal received from the motor controller 130, the current informationselector 125 selects the current controller 121 for transmitting thecurrent control information and transmits the current controlinformation to the current controller 121 (step S607).

The current controller 121 supplies a driving current to the coil unit101 in accordance with the current control information received from themotor controller 130 (step S608). A thrust according to the supplieddriving current is generated in the truck 111. The truck 111 is moved bythe generated thrust. That is, in the coil unit 101 to which the drivingcurrent was supplied, magnetic forces which repel magnetic forces of themagnets 114 to 116 of the truck 111 are generated from the coils 105U,105V, and 105W of the respective phases. The truck 111 is moved by thegenerated thrust.

Subsequently, the control of FIG. 5B will be described. In FIG. 5B, thetruck 111 is located near a boundary between the coil units 101 and 102and the truck 112 is located near a boundary between the coil units 103and 104, respectively. In FIG. 5B, the position P2 indicates a stopposition of the truck 111 and the position P3 indicates a stop positionof the truck 112. The truck 111 stops in such a manner that a center ofthe magnet 115 of the truck 111 coincides with the position P2. In FIG.5B, since processes are common to those in steps S601 to S603 in FIG. 6described in FIG. 5A, their description is omitted. In FIG. 5B, thecontrol of the truck 111 which is made by the motor controller 130 andthe control of the truck 112 which is made by the motor controller 140are common. Therefore, the control of the truck 111 which is made by themotor controller 130 will be described hereinbelow.

The motor controller 130 arithmetically operates control deviationinformation as a difference between the target position of the truck 111and the present position of the truck 111 detected by the opticalencoder 161 (step S604). From the position of the truck 111 which wasinput to the control deviation calculator 132, the motor controller 130can detect that the positional relation between the position of thetruck 111 and the coil unit 101 became the position P2 as a stopposition which has been preset into the motor controller.

On the basis of the control deviation information calculated by thecontrol deviation calculator 132, the position controller 133arithmetically operates current control information and forms a currentcontrol information exchange signal (step S605). The current controlinformation exchange signal which is formed in step S605 is such asignal that the current information selector 125 can select the currentcontrollers 121 and 125 necessary to stop the truck 111 at the positionP2. The current control information which is obtained in step S605 isone current control information irrespective of the number of currentcontrollers which are selected. The motor controller 130 transmits theobtained current control information and the formed current controlinformation exchange signal to the current information selector 125(step S606).

On the basis of the current control information exchange signal receivedfrom the motor controller 130, the current information selector 125selects the two current controllers 121 and 122 from the currentcontrollers 121 to 124 and switches them, and transmits the currentcontrol information (step S607). On the basis of the received currentcontrol information, the current controllers 121 and 122 supply drivingcurrents to the coil units 101 and 102 (step S608). In the coil units101 and 102 to which the driving currents were supplied, magnetic forcesadapted to absorb magnetic forces of the magnets 114 to 116 aregenerated from the coils 105U, 105V, and 105W of the respective phases.

In FIG. 5B, the two current controllers 121 and 122 are driven by onecurrent control information transmitted from the motor controller 130and one truck 111 stops at the stop position P2. Thus, the truck 111 canbe stopped at a high precision in a short time. For example, the truck111 can be stopped from the target stop position P2 at a precision of afew μm for a period of time of tens of milliseconds after the truck 111reached the stop target position P2.

After the trucks 111 and 112 illustrated in FIG. 5B were stopped, therunning controller 20 transmits a start signal for instructing that themovement of the trucks is started in a lump to all of the motorcontrollers. Each motor controller receives the start signal through thecontroller. Thus, the trucks 111 and 112 illustrated in FIG. 5B startthe movement to the next stop target position.

Subsequently, FIG. 5C will be described. FIG. 5C differs from FIG. 5Awith respect to a point that the new truck 113 enters and the truck 111moves over the coil units 102 and 103. Other control is common.Therefore, a description of the common portions is omitted.

Although the truck 111 moves to the control areas 402 and 403 which aredriven by the two coil units 102 and 103 in FIG. 5C, the motorcontroller 130 continuously controls the truck 111. Similarly, the motorcontroller 140 continuously controls the truck 112. The control of thetruck 111 which moves over the coil units 102 and 103 will be describedhereinbelow.

Since the truck 111 has entered the control area 402 of the coil unit102, the optical encoder 162 detects the position of the truck 111 (stepS601). The controller 170 determines whether or not the truck 111detected by the optical encoder 162 is a truck which has entered newly(step S602). Since the truck 111 is not the truck which has enterednewly (NO in step S602), the processing routine advances to step S604.

The motor controller 130 arithmetically operates the control deviationinformation as a difference between the target position of the truck 111and the position of the truck 111 detected by the optical encoder 162(step S604). From the position of the truck 111 which was input to thecontrol deviation calculator 132, the motor controller 130 can detectthat the position of the truck 111 became the position over the coilunits 102 and 103.

The position controller 133 arithmetically operates the current controlinformation so that the truck 111 can move over the coil units 102 and103 and the current information selector 125 forms such a currentcontrol information exchange signal that the current informationselector 125 can select the current controllers 122 and 123 (step S605).As mentioned above, the current control information which is obtained instep S605 is one current control information irrespective of the numberof current controllers which are selected. The motor controller 130transmits the arithmetically operated current control information andthe formed current control information exchange signal to the currentinformation selector 125 (step S606).

The current information selector 125 switches the current controllersfrom the current controllers 121 and 122 to the current controllers 122and 123 on the basis of the current control information exchange signalreceived from the motor controller 130 and transmits the current controlinformation to the current controllers 122 and 123 (step S607). Thecurrent controllers 122 and 123 supply the driving currents to the coilunits 102 and 103 on the basis of the current control informationreceived from the current information selector 125, respectively (stepS608). In the coil units 102 and 103 to which the driving currents weresupplied, magnetic forces which repel magnetic forces of the magnets 114to 116 of the truck 111 are generated from the coils 105U, 105V, and105W of the respective phases. The truck 111 is moved by the generatedthrust.

Subsequently, the control of the truck 113 which enters from theadjacent linear motor control apparatus 10 a will be described. Theposition of the truck 113 which entered newly the control area 401 whichcan be controlled by the coil unit 101 is detected by the opticalencoder 161 (step S601). The controller 170 determines whether or notthe truck 113 detected by the optical encoder 161 is a new truck (stepS602). The controller 170 determines that the truck 113 is the new truckwhich entered the linear motor module 10 b (YES in step S602) andallocates the motor controller 150 which is in the rest state to thetruck 113 (step S603). In detail, the processes will be described withreference to the flowchart shown in FIG. 7.

The flowchart shown in FIG. 7 relates to the processes which areexecuted by the controller 170 and is started when the controller 170has detected that the position information of the new truck was detectedby the optical encoder 161.

The controller 170 determines whether or not the motor controller 130 iscontrolling the truck or is in the rest state (step S701). When themotor controller 130 is in the rest state (YES in step S701), thecontroller 170 allocates the truck 113 detected by the optical encoder161 to the motor controller 130 (step S702). The controller 170transmits the allocated information as an allocation signal to theposition information selector 165.

When the motor controller 130 is controlling the truck (NO in stepS701), the controller 170 determines whether or not the motor controller140 is controlling the truck or is in the rest state (step S703). Whenthe motor controller 140 is in the rest state (YES in step S703), thecontroller 170 allocates the truck 113 detected by the optical encoder161 to the motor controller 140 (step S704). The controller 170transmits the allocated information as an allocation signal to theposition information selector 165.

When the motor controller 140 is controlling the truck (NO in stepS703), the controller 170 determines whether or not the motor controller150 is controlling the truck or is in the rest state (step S705). Whenthe motor controller 150 is in the rest state (YES in step S705), thecontroller 170 allocates the truck 113 detected by the optical encoder161 to the motor controller 150 (step S706). The controller 170transmits the allocated information as an allocation signal to theposition information selector 165.

On the other hand, when the motor controller 150 is controlling thetruck (NO in step S705), this means that the motor controller to whichthe truck 113 detected by the optical encoder 161 can be allocated doesnot exist. Therefore, the controller 170 transmits error information tothe running controller 20 (step S707). The running controller 20 whichreceived the error information from the controller 170 may, for example,stop the control of the trucks of all of the linear motor modules 10 ato 10N. In FIG. 5C, the motor controller 150 is allocated to theposition information of the truck 111.

The motor controller 150 obtains, through the position informationselector 165, the position information of the truck 113 detected by theoptical encoder 161. The position commander 151 outputs position commandinformation corresponding to the target position illustrated in FIG. 4Bto the control deviation calculator 152. The control deviationcalculator 152 arithmetically operates control deviation informationserving as a difference between the target position which was input fromthe position commander 151 and the position information of the truck 113detected by the optical encoder 161 (step S604).

The position controller 153 arithmetically operates current controlinformation including a magnitude and a direction of the current on thebasis of the control deviation information and forms a current controlinformation exchange signal for selecting the current controller (stepS605). In FIG. 5C, since the truck 113 is located in the control area401 of the coil unit 101, the position controller 153 forms such acurrent control information exchange signal that the current informationselector 125 can select the current controller 121. The motor controller150 transmits the current control information and the current controlinformation exchange signal to the current information selector 125(step S606).

On the basis of the current control information exchange signal receivedfrom the motor controller 150, the current information selector 125selects the current controller 121 and transmits the current controlinformation to the current controller 121 (step S607). The currentcontroller 121 supplies a driving current to the coil unit 101 on thebasis of the current control information received through the currentinformation selector 125 (step S608). In the coil unit 101 to which thedriving current was supplied, the magnetic forces which repel themagnetic forces of the magnets 114 to 116 of the truck 113 are generatedfrom the coils 105U, 105V, and 105W of the respective phases. The truck113 is moved by the generated thrust.

As mentioned above, the truck 113 is controlled by the motor controller150, current controller 121, coil unit 101, current information selector125, and position information selector 165 shown by double lines in FIG.5C.

The truck 112 illustrated in FIG. 5C moves to the linear motor module 10c adjacent to the linear motor module 10 b. The motor controller 140which has controlled the truck 112 transmits control state informationshowing that it is in the rest state to the controller 170.

After the control state illustrated in FIG. 5C, the motor controller 140is shifted to the control state illustrated in FIG. 5D. In FIG. 5D, thetrucks 111 and 113 are controlled based on the flowchart of FIG. 6 in amanner similar to FIGS. 5A to 5C. The positions P2 and P3 illustrated inFIG. 5D are the stop positions of the trucks 111 and 113 in a mannersimilar to FIG. 5B. In FIG. 5D, although the truck 111 moves to thecontrol areas 403 and 404 which are driven by the coil units 103 and104, the motor controller 130 continuously controls the truck 111.Similarly, the motor controller 150 continuously controls the truck 113.The motor controller 140 shown by a broken line is in the rest state inassociation with the movement of the truck 112. The optical encoders 162and 164 enter a state where they do not contribute to the control of thetrucks.

The control which is made by the motor controllers 130 and 150 is commonto the processes described in FIG. 5B but merely differs with respect toa point that the optical encoders for detecting the positions of thetrucks, the current controllers for supplying the currents, and the coilunits differ. Therefore, a description of the control of FIG. 5D isomitted here. In FIG. 5D, by making the control in a manner similar toFIG. 5B, after the truck 111 reached the stop target position P3, it canstop in a short time. Similarly, after the truck 113 reached the stoptarget position P1, it can stop in a short time.

After that, when all of the motor controllers existing in the linearmotor control system 1 receive the start signal transmitted from therunning controller 20, the trucks 111 and 113 illustrated in FIG. 5Dstart the movement from the stop position to the next target position.When a new truck (not shown) enters the control range of the linearmotor module 10 b, the motor controller 140 in the rest state isallocated and the motor controller 140 controls the new truck. Thecontrol of the trucks in FIG. 5D and subsequent diagrams is repetitivelymade in accordance with the foregoing control.

As mentioned above, in the embodiment, since the current informationselector 125 switches the current controllers which input the currentcontrol information, it can select and switch one or a plurality ofcurrent controllers serving as input destinations of each currentcontrol information for a plurality of current control information. Whena plurality of current controllers are selected by the currentinformation selector 125, each current controller supplies the drivingcurrent to the corresponding coil units on the basis of one currentcontrol information. Thus, one or a plurality of coil units can bedriven in accordance with the position of the truck. Even when the truckis located near the boundary between the coil units, the drivingcurrents which are almost equal can be supplied to each coil unit.Therefore, the magnetic forces which are generated from a plurality ofcoil units are almost equal, a repulsion or an attraction which acts onthe truck from each coil unit are also almost equal, and the operationof the truck becomes stable. Therefore, a plurality of trucks which moveat a high speed can be controlled at a high precision.

Since the trucks can be stopped at a high precision even near theboundary between the coil units, the restriction of the stop position ofthe truck in the linear motor module can be reduced. Since the samemotor controller controls the truck until the truck which entered onelinear motor module is ejected, there is no need to switch the motorcontrollers and the truck can be controlled at a higher speed.Therefore, the movement and stop of all of the trucks existing in thelinear motor module can be controlled. In the embodiment, a series ofcontrol for moving and stopping all of the trucks at tens of kHz, forexample, 10 kHz can be repeated.

Second Embodiment

A linear motor control system according to the second embodiment of theinvention will be described hereinbelow. The second embodiment differsfrom the first embodiment with respect to a point that, in the linearmotor module, a combination as motor controllers is abandoned and acontrol deviation information selector is provided in place of thecurrent information selector. Other construction is common. Therefore,the same component elements as those in the first embodiment aredesignated by the same reference numerals and their description isomitted here.

FIG. 8 is a schematic constructional diagram of the linear motor module100 a according to the second embodiment of the invention. Asillustrated in FIG. 8, control deviation calculators 181 to 183 areconnected to a control deviation information selector 184 as a switchingunit. The control deviation information selector 184 is connected toposition controllers 191 to 194. The position controllers 191 to 194 areconnected to the current controllers 121 to 124, respectively.

The control deviation calculators 181 to 183 arithmetically operatecontrol deviation information serving as differences between the targetpositions of the trucks which were input from the position commanders131, 141, and 151 and the present positions of the trucks which weretransmitted from the optical encoders 161 to 164, respectively. Thecontrol deviation calculators 181 to 183 form control deviationinformation exchange signals to select one or a plurality of positioncontrollers 191 to 194 for driving the coil units necessary to controlthe truck as a control target and transmit to the control deviationinformation selector 184.

On the basis of the control deviation information exchange signals whichwere input from the control deviation calculators 181 to 183, thecontrol deviation information selector 184 selects and switches one or aplurality of position controllers 191 to 194 as input destinations ofthe control deviation information which is output from the controldeviation calculators 181 to 183. The control deviation informationselector 184 transmits the control deviation information to the positioncontroller combined with any one of the control deviation calculators181 to 183. On the basis of the control deviation information, theposition controller which received the control deviation informationfrom the control deviation information selector 184 arithmeticallyoperates current control information necessary to control the trucks andtransmits to the corresponding current controller. The driving profiletransmitted from the running controller 20 may be stored into a memory(not shown) which can be accessed from the position commanders 131, 141,and 151.

FIG. 9 is a detailed diagram of the position controllers and the currentcontrollers in the linear motor module 100 a in the embodiment. Thetruck control in the embodiment will now be described in detail withreference to FIG. 9. A symbol d in FIG. 9 denotes that it is coupledwith the corresponding symbol d. The truck 111 operates in response to aposition control command which is transmitted from the positioncommander 131. In FIG. 9, the position commander 141 is in a rest statewhere the truck control is not made.

The position of the truck 111 is detected by the optical encoders 161and 162. The optical encoders 161 and 162 transmit the detected positioninformation to the position information selector 165. The positioninformation selector 165 transmits the present position of the truck 111detected by the optical encoder 161 to the control deviation calculator181.

The control deviation calculator 181 calculates a difference between theposition control command which is output from the position commander131, that is, the target position of the truck 111 and the receivedposition and arithmetically operates control deviation information e(t).The control deviation calculator 181 forms a control deviationinformation exchange signal so as to output the control deviationinformation e(t) from the control deviation information selector 184 tothe position controllers 191 and 192, and transmits the controldeviation information and the control deviation information exchangesignal to the control deviation information selector 184.

The position controllers 191 and 192 perform PID control. Proportionalgains 512 and 522 are input to integration calculators 514 and 524 anddifferential calculators 515 and 525, respectively. The integrationcalculators 514 and 524 perform a calculation of the followingexpression (1).

$\begin{matrix}{\frac{1}{T_{I}}{\int_{t - \tau}^{t}{{e(t)}{dt}}}} & (1)\end{matrix}$

In the expression (1), T₁ denotes an integral time, t indicates a time,and τ denotes a time interval to perform an integration, respectively.

The differential calculators 515 and 525 perform a calculation of thefollowing expression (2).

$\begin{matrix}{T_{D}\frac{{de}(t)}{dt}} & (2)\end{matrix}$

In the expression (2), T_(D) denotes a differential time.

Sums obtained from calculation results of the expressions (1) and (2)and the proportional gains 512 and 522 are current control informationm₁(t) and m₂(t), respectively. Now, assuming that current controlinformation is expressed by m(t), it is obtained by the followingequation (3).

$\begin{matrix}{{m(t)} = {K_{p}\left\{ {{e(t)} + {\frac{1}{T_{I}}{\int_{t - \tau}^{t}{{e(t)}{dt}}}} + {T_{D}\frac{{de}(t)}{dt}}} \right\}}} & (3)\end{matrix}$

In the equation (3), K_(P) denotes a proportional gain.

The current control information m₁(t) and m₂(t) are calculated by usingthe equation (3) and the current control information m₁(t) and m₂(t) areinput to the current controllers 121 and 122, respectively.

The current controllers 121 and 122 have current deviation calculators513 and 523, current information proportional units 517 and 527, andcurrent information integrators 518 and 528, respectively. The currentinformation proportional units 517 and 527 perform a gain adjustment byparameters which can be arbitrarily set. Current feedback informationFB₁ and FB₂ are information based on the driving currents of therespective phases of the U phase, V phase, and W phase and are input tothe current deviation calculators 513 and 523, respectively.

A control method of the current controllers will be described by usingthe current controller 121. Since the current controller 122 has aconstruction similar to that of the current controller 121, itsdescription is omitted.

The current deviation calculator 513 calculates a difference between thecurrent control information m₁(t) and the current feedback informationFB₁. On the basis of the difference between the current controlinformation m₁(t) and the current feedback information FB₁, the currentinformation proportional unit 517 performs a proportional calculationand the current information integrator 518 performs an integralcalculation. On the basis of the sum of a proportional calculationresult calculated by the current information proportional unit 517 andan integral calculation result calculated by the current informationintegrator 518, that is, on the basis of the current controlinformation, the current controller 121 supplies driving currents to thecoils 105U, 105V, and 105W of the respective phases provided for thecoil unit 101. Thus, the magnetic forces are generated in the coils105U, 105V, and 105W of the respective phases. By the magnetic forces ofthe magnets 114 to 116 and the magnetic forces generated in the coils105U, 105V, and 105W of the respective phases, the truck 111 is moved toa position where a balance of the magnetic force relation can beobtained, that is, to a stable magnetic field.

The control of the linear motor module according to the embodiment willnow be described. FIG. 10A shows a control state illustrating themovement of the trucks 111 and 112. FIG. 10B shows a control stateillustrating the stop of the trucks 111 and 112. FIG. 10C shows acontrol state at the time when the new truck 113 has entered. FIG. 10Dshows a control state illustrating the stop of the trucks 111 and 113.FIG. 11 is a flowchart illustrating the control of the trucks accordingto the embodiment. FIG. 12 is a flowchart illustrating an allocatingprocess of the trucks in FIG. 11. The control will now be describedhereinbelow with reference to FIGS. 10 to 12. In FIGS. 10A to 10D, thepositional relations between the trucks and the coil units in the caseof moving a plurality of trucks by controlling them and the controlstate of each controller for controlling the truck are time-sequentiallyshown. In FIGS. 10A to 10D, the control states in the linear motormodule 100 b are illustrated. It is assumed that the linear motor module100 b is located adjacently between the linear motor modules 100 a and100 c. In a flowchart illustrated in FIG. 11, a process of step S1101 iscommon to step S601 in FIG. 6 described in the first embodiment.Therefore, a description of common portions is omitted.

As illustrated in FIG. 10A, when the truck 111 is located in an areawhich can be controlled only by the coil unit 101, the control of thetruck 111 is made by the position commander 131, control deviationcalculator 181, position controller 191, and current controller 121. InFIG. 10A, it is assumed that the control deviation calculator and theposition commander have already been allocated to the trucks 111 and112. A description of steps S1101 to S1103 in FIG. 11 is omitted. Sincethe control to the trucks 111 and 112 is the same, only the control tothe truck 111 will be described.

The control deviation calculator 181 calculates the control deviationinformation e(t) serving as a difference between the target position ofthe truck 111 which was input from the position commander 131 and thepresent position of the truck 111 (step S1104). In step S1104, thecontrol deviation information selector 184 also forms a controldeviation information exchange signal to select the position controllerfor controlling the coil units necessary to control the truck 111.

The control deviation calculator 181 transmits the obtained controldeviation information e(t) and the formed control deviation informationexchange signal to the control deviation information selector 184 (stepS1105). On the basis of the control deviation information exchangesignal, the control deviation information selector 184 selects theposition controller to transmit the control deviation informationobtained in step S1104 and transmits the control deviation informationto the selected position controller (step S1106). In FIG. 10A, on thebasis of the control deviation information exchange signal, the controldeviation information selector 184 selects the position controller 191and transmits the control deviation information obtained in step S1104to the position controller 191.

On the basis of the received control deviation information, the positioncontroller 191 arithmetically operates the current control informationm₁(t) to control the current controller 121 and transmits thearithmetically operated current control information to the currentcontroller 121 (step S1107). The current controller 121 supplies acurrent to the coil unit 101 on the basis of the received currentcontrol information (step S1108).

Subsequently, as illustrated in FIG. 10B, the truck 111 moves to theposition which can be controlled by the two coil units 101 and 102. InFIG. 10B, the control differs from FIG. 10A with respect to a point thatthe truck 111 is controlled by the two coil units. Therefore, adescription about steps S1101 to 51103 in FIG. 11 is omitted.

The control deviation calculator 181 calculates the control deviationinformation e(t) serving as a difference between the target position ofthe truck 111 which was input from the position commander 131 and thepresent position of the truck 111 and forms a control deviationinformation exchange signal (step S1104). The control deviationinformation exchange signal which is formed in step S1104 is such asignal that the position controllers 191 and 192 are selected.

The control deviation calculator 181 transmits the obtained controldeviation information and the formed control deviation informationexchange signal to the control deviation information selector 184 (stepS1105). On the basis of the received control deviation informationexchange signal, the control deviation information selector 184 selectsand switches the two position controllers 191 and 192, switches the twoposition controllers 191 and 192 from the position controller 191, andtransmits the received control deviation information e(t) to the twoposition controllers 191 and 192 (step S1106).

On the basis of the received control deviation information e(t), theposition controllers 191 and 192 arithmetically operate the currentcontrol information m₁(t) and m₂(t) serving as currents which aresupplied to the coil units 101 and 102, respectively (step S1107). Theposition controller 191 transmits the obtained current controlinformation m₁(t) to the current controller 121. The current controller121 supplies a driving current to the coil unit 101 on the basis of thecurrent control information m₁(t). The position controller 192 transmitsthe obtained current control information m₂(t) to the current controller122. The current controller 122 supplies a driving current to the coilunit 102 on the basis of the current control information m₂(t) (stepS1108). A difference between the current control information m₁(t) andm₂(t) in the above control relates only to values which are calculatedby the integration calculators 514 and 524.

In the embodiment, the time interval T during which the integrationcalculators 514 and 524 perform the integration is set to a time shorterthan a time which is required until the truck 111 stops at the stopposition after the position controller 192 started the control of thetruck 111. Thus, at time when the truck 111 stops at the stop positionP2, a difference between the values calculated by the two integrationcalculators 514 and 524 is sufficiently small and a difference betweenthe two current control information m₁(t) and m₂(t) is also sufficientlysmall.

On the basis of the current control information m₁(t) and m₂(t), thecurrent controllers 121 and 122 drive the two coil units 101 and 102 bythe driving currents which are almost equal. Thus, the truck 111 can bestopped at the position P2 serving as a boundary position between thetwo coil units 101 and 102 in a short time at a high precision.

Although it is desirable that the current control information m₁(t) andm₂(t) have the same value, even if they do not have the same value, thetruck can be stopped at the boundary position between the two coil unitsin a short time at a high precision so long as such a construction thatthe two position controllers are controlled based on one controldeviation information e(t) is used. So long as such a construction thatthe two position controllers are controlled based on one controldeviation information e(t) is used, a PID control parameter of eachposition controller can be finely adjusted and, for example, controlcorresponding to an individual difference caused by an attachingprecision of every coil unit can be made.

FIG. 10C differs from FIGS. 10A and 10B with respect to a point that thenew truck 113 enters the control range of the coil unit 101 and thetruck 112 is ejected from the linear motor module 100 b. Therefore, adescription of common portions is omitted. First, the entering of thetruck 113 will be described hereinafter.

The optical encoder 161 detects the position of the truck 113 (stepS1101). The position information of the truck 113 detected by theoptical encoder 161 is input to the controller 170 through the positioninformation selector 165. Subsequently, the controller 170 determineswhether or not the truck 113 detected by the optical encoder 161 is anew truck (step S1102). The controller 170 determines that the truck 113is the new truck which entered the linear motor module 100 b (YES instep S1102) and executes the allocating process of the truck 113 (stepS1103).

As illustrated in FIG. 12, the controller 170 determines whether or notthe control deviation calculator 181 is controlling the truck or is in arest state (step S1201). When the control deviation calculator 181 is inthe rest state (YES in step S1201), the controller 170 allocates thetruck detected by the optical encoder 161 to the control deviationcalculator 181 (step S1202). The controller 170 transmits the allocatedinformation as an allocation signal to the control deviation calculator181.

When the control deviation calculator 181 is controlling the truck (NOin step S1201), the controller 170 determines whether or not the controldeviation calculator 182 is controlling the truck or is in a rest state(step S1203). When the control deviation calculator 182 is in the reststate (YES in step S1203), the controller 170 allocates the truckdetected by the optical encoder 161 to the control deviation calculator182 (step S1204). The controller 170 transmits the allocated informationas an allocation signal to the control deviation calculator 182.

When the control deviation calculator 182 is controlling the truck (NOin step S1203), the controller 170 determines whether or not the controldeviation calculator 183 is controlling the truck or is in a rest state(step S1205). When the control deviation calculator 183 is in the reststate (YES in step S1205), the controller 170 allocates the truckdetected by the optical encoder 161 to the control deviation calculator183 (step S1206). The controller 170 transmits the allocated informationas an allocation signal to the control deviation calculator 183.

When the control deviation calculator 183 is controlling the truck (NOin step S1205), this means that the control deviation calculator towhich the truck detected by the optical encoder 161 can be allocateddoes not exist. Therefore, the controller 170 transmits errorinformation to the running controller 20 (step S1207). In FIG. 10C,since the control deviation calculator 183 is in the rest state, thecontroller 170 allocates the control deviation calculator 183 to thecontrol of the truck 113. With respect to the truck 113 which enterednewly, since the processes in step S1104 and subsequent steps in FIG. 11are common to those described in FIGS. 10A and 10B, their description isomitted.

The truck 112 illustrated in FIG. 10C moves to the linear motor module100 c adjacent to the linear motor module 100 b by the series ofprocesses illustrated in FIG. 11. The control deviation calculator 182transmits control state information showing that it entered the reststate where there is no truck as a control target to the controller 170.

The trucks 111 and 113 in FIG. 10D are controlled in accordance withtheir positions as described in FIGS. 10A and 10B. As illustrated inFIGS. 10A to 10D, the truck which entered the linear motor module 100 bis continuously controlled by the control deviation information e(t)which is transmitted from one control deviation calculator until thetruck is ejected to the outside of the control range of the linear motormodule 100 b.

As mentioned above, in the embodiment, on the basis of the controldeviation information exchange signal, the control deviation informationselector 184 selects and switches one or a plurality of positioncontrollers which input one control deviation information. Thus, withrespect to a plurality of control deviation information, the controldeviation information selector 184 can select and switch one or aplurality of position controllers serving as input destinations of eachcontrol deviation information. If the plurality of position controllersare selected by the control deviation information selector 184, eachposition controller arithmetically operates the current controlinformation m(t) on the basis of one control deviation information e(t)and transmits to each current controller. Since each current controllersupplies a driving current to the corresponding coil unit on the basisof the current control information m(t), an effect similar to that inthe first embodiment can be obtained. Since the controller 170 allocatesthe truck which entered newly to each of the plurality of controldeviation calculators 181 to 183, even if a plurality of trucks arearranged at a high density, each truck can be moved at a high speed andstopped at a high precision. The PID control of the position controllersand the control method of the current controllers described in theembodiment are an example and the control method is not limited by them.

Third Embodiment

A manufacturing system 800 of articles according to the third embodimentof the invention will be described with reference to FIG. 13. Themanufacturing system 800 of articles has: the linear motor controlsystem 1 according to the first embodiment; processing apparatuses 810and 811; and a process controller 820. The linear motor control system 1conveys a work 801 between the processing apparatuses 810 and 811. Inthis instance, the articles denote, for example, a toner cartridge foran ink jet printer or a copying apparatus, parts for a camera,semiconductor products, and the like. The process controller 820collects process information of the processing apparatuses 810 and 811and forms a conveying process of the truck. The number of processingapparatuses 810 and 811 is not limited to two.

A manufacturing method of articles by the manufacturing system 800 willbe described. The running controller 20 transmits group conveyingcommands to the motor controller 130 in a lump at the same timing. Themotor controller 130 receives the group conveying commands. In responseto those commands, the motor controller 130 arithmetically operatescontrol deviation information on the basis of the information of thetarget position of the truck which has previously been received from therunning controller 20 for the truck which exists in or entered thecorresponding linear motor module. The motor controller 130arithmetically operates current control information on the basis of thedeviation information and forms a current control information exchangesignal. The current information selector (not shown) switches one or aplurality of current controllers on the basis of the current controlinformation exchange signal. The switched current controllers supply thedriving currents to the coil units on the basis of the received currentcontrol information. Thus, the truck 111 on a conveying path 830 isconveyed toward the first and second processing apparatuses 810 and 811.The work 801 is grasped and mounted on the truck 111. The processingapparatuses 810 and 811 to which the truck 111 was conveyed executepredetermined processes to the work 801.

For example, if the article to be manufactured is a toner cartridge foran ink jet printer, the work 801 is a cartridge to enclose toner powder.The processing apparatus 810 executes a process for enclosing tonerpowder for a color ink into the work 801. The processing apparatus 811executes a process for enclosing toner powder for a black ink into thework 801. Finally, an ink cartridge product is manufactured as anarticle 802.

As mentioned above, the manufacturing system of articles according tothe embodiment can manufacture the articles in accompanied with anadvantage of the linear motor control system according to the firstembodiment. Thus, not only a manufacturing efficiency of articles can beimproved but also manufacturing costs can be reduced. The manufacturingsystem of articles according to the embodiment can be also applied tothe linear motor control system according to the second embodiment.

Although the exemplary embodiments have been described above, theinvention is not limited to the foregoing embodiments but variousmodifications are possible within a scope without departing from thespirit of the invention.

For example, although the first and second embodiments have such aconstruction that the linear motor modules 10 a to 10N have the fourcoil units 101 to 104, it is sufficient to use a linear motor modulehaving two or more coil units and two or more motor controllers. Byconstructing the system as mentioned above, since each motor controlleris allocated every truck which enters the linear motor module, the truckcan be precisely stopped even at a boundary between the coil units.

Although the 3-phase linear motor has been used in each of the foregoingembodiments, the invention is not limited to three phases but, forexample, a 2-phase linear motor may be used. The number of magnets 114to 116 is not limited to 3 either.

Although the coil units 101 to 104 are serially connected in theforegoing first and second embodiments, the layout of the coil units isnot limited to such a construction but the coil units may be arranged,for example, as illustrated in FIGS. 14A and 14B. FIG. 14A is a top viewof the linear motor module. FIG. 14B is a cross sectional view takenalong the line 14B-14B in FIG. 14A. As illustrated in FIG. 14A, such aT-type layout that two sets of coil units 101 a to 103 a and 101 b to103 b are arranged so as to sandwich the magnets 114 to 116 of a truck901 may be used.

If the system has such coil units 101 a to 103 a and 101 b to 103 b, thetruck 901 has a magnet bracket 902, the magnets 114 to 116, four movingblocks 903, and the scale 205. The moving blocks 903 and the two rails201 and 201 construct a linear guide. In the case of arranging the coilunits in a T shape, the two opposite coil units 101 a and 101 b arearranged so that a plurality of coils 105 forming the respective phasesare serially connected. This is true of the opposite coil units 102 aand 102 b and the opposite coil units 103 a and 103 b.

Other Embodiments

Embodiment(s) of the present invention can also be realized by acomputer of a system or apparatus that reads out and executes computerexecutable instructions (e.g., one or more programs) recorded on astorage medium (which may also be referred to more fully as a‘non-transitory computer-readable storage medium’) to perform thefunctions of one or more of the above-described embodiment(s) and/orthat includes one or more circuits (e.g., application specificintegrated circuit (ASIC)) for performing the functions of one or moreof the above-described embodiment(s), and by a method performed by thecomputer of the system or apparatus by, for example, reading out andexecuting the computer executable instructions from the storage mediumto perform the functions of one or more of the above-describedembodiment(s) and/or controlling the one or more circuits to perform thefunctions of one or more of the above-described embodiment(s). Thecomputer may comprise one or more processors (e.g., central processingunit (CPU), micro processing unit (MPU)) and may include a network ofseparate computers or separate processors to read out and execute thecomputer executable instructions. The computer executable instructionsmay be provided to the computer, for example, from a network or thestorage medium. The storage medium may include, for example, one or moreof a hard disk, a random-access memory (RAM), a read only memory (ROM),a storage of distributed computing systems, an optical disk (such as acompact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™),a flash memory device, a memory card, and the like.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2014-086367, filed on Apr. 18, 2014, which is hereby incorporated byreference herein in its entirety.

1.-7. (canceled)
 8. A control apparatus to control moving of a truck ina control area comprising: a plurality of controllers configured tocontrol moving of the truck in the control area of the controlapparatus; and a selector configured to control for allocating any oneof the plurality of controllers to the truck in the control area,wherein the selector controls such that: when a first controller isallocated to a first truck and a second truck enters the control area ofthe control apparatus, a second controller not allocated to any one ofthe tracks among the plurality of controllers is allocated to the secondtruck, and when the first truck is ejected from the control area, thefirst controller is shifted to a state not to control the first truck.9. The control apparatus according to claim 8, wherein the truck iscapable of moving by receiving a magnetic field generated by a pluralityof coils arranged in the control area, and the plurality of controllerscontrol which of the plurality of coils the current flows.
 10. Thecontrol apparatus according to claim 9, further comprising a positiondetecting unit configured to detect position of the truck in the controlarea; and a current control unit configured to control current flowingin the plurality of coils, based on a difference between the position ofthe truck detected by the position detecting unit and a target positionof the truck.
 11. The control apparatus according to claim 9, furthercomprising a rail forming a path through which the track moves, and theplurality of coils are arranged along the rail.
 12. A conveying systemcomprising a plurality of the control apparatus according to claim 9,the plurality of the control apparatus are connected to each other. 13.The conveying system according to claim 12, further comprising a runningcontroller configured to output a conveying instruction to the pluralityof the control apparatus connected to each other.
 14. The conveyingsystem according to claim 13, wherein the running controller, inresponse to receiving error information from any one of the plurality ofthe control apparatus, outputs a stop instruction to the other of theplurality of the control apparatus.
 15. A controlling method of acontrol apparatus to control moving of a truck in a control areacomprising: a plurality of controllers configured to control moving ofthe truck in the control area of the control apparatus; a selectorconfigured to control for allocating any one of the plurality ofcontrollers to the truck in the control area; and a detecting unitconfigured to detect entering the truck into the control area, whereinthe controlling method comprises: a detecting step of detecting enteringby the detecting unit, when a first controller is allocated to a firsttruck, entering a second truck into the control area; an allocating stepof, in response to detecting the entering the second truck into thecontrol area, allocating a second controller not allocated to any one ofthe tracks among the plurality of controllers, to the second truck; anda shifting step of shifting, by the selector, the first controller to astate not to control the first truck when the first truck is ejectedfrom the control area.
 16. The controlling method according to claim 15,wherein the truck is capable of moving by receiving a magnetic fieldgenerated by a plurality of coils arranged in the control area, and theplurality of controllers control which of the plurality of coils thecurrent flows.
 17. The controlling method according to claim 15, furthercomprising a position detecting step configured to detect position ofthe truck in the control area; and a current control step configured tocontrol current flowing in the plurality of coils, based on a differencebetween the position of the truck detected in the position detectingstep and a target position of the truck.
 18. The controlling methodaccording to claim 15, wherein a receiving step of receiving, by arunning controller, error information from any one of the plurality ofthe control apparatus; and a transmitting step of, in response to thereceiving the error information, transmitting a stop instruction to theother of the plurality of the control apparatus.
 19. A manufacturingmethod of an article comprising: executing a process of subjecting awork placed on the truck to a predetermined step, according to thecontrolling method of claim 15.